Pion absorption by deuterons in field theory

Using non-perturbative, field-theoretic techniques based on a generalization of the Low equation, an inhomogeneous, coupled, linear, integral equation is developed for the reaction matrix for πd→2p. The inhomogeneous term in this equation consists of a truncated, multiple-scattering expansion of the breakup process. The integral terms couple the reaction to elastic nucleon-nucleon and elastic pion-deuteron scattering. The inhomogeneous term is evaluated at the reaction threshold, with relativistic forms for the absorption and rescattering vertices. P-wave pion-nucleon rescattering is found to make a non-negligible contribution to the s-wave absorption process at threshold